Photomultiplier Detector

A photomultiplier contains a photosensitive surface that absorbs radiation in the ultraviolet, visible, or near IR, producing an electrical current proportional to the number of photons reaching the photomultiplier. As shown here, a photon strikes the photoemissive cathode producing electrons, which accelerate toward a positively charged dynode. Collision of these electrons with the dynode generates additional electrons, which accelerate toward the next dynode. A total of 10⁶–10⁷ electrons per photon eventually reach the anode, generating an electrical current.